My spectrum analyser is a Siglent SVA1032X, good for 3.2 GHz.
I'll have to get a down converter for my scope...
It's all SMD (I even mounted the resistors upside down to improve performance) and the entire signal path is 'coplanar waveguide with ground' at almost exactly 50ohms.
I haven't completely given up just yet, but I took the cheater's way out... I just ordered some MB510-PF prescalers from China, the same part that HP used. :D
I'll replicate the HP bias network, with the only main differences in my design being the 5V LDO regulator rather than a zener regulator, and the RF amps/diodes being substituted too as they are obsolete and my selections all seem to work fine.
I have just re-laid out the PCB for the new prescaler, so once I've slept overnight and looked at it again tomorrow with fresh eyes and fixed any stupid mistakes, I'll send the gerbers off to get the PCB's made and wait for the prescaler chips to come from China.
At least if I get a closer replica working to HP specs with a HP specified prescaler, I can use that as a baseline for further tweaking if needed.
One other question. I'm not sure if I'm doing it right, but I tried measuring the SWR of the input using the SWR function of my VNA for fun. Does this look correct/reasonable/etc or does SWR not matter for this application? I'm still learning what I'm looking at here..
Jared.
Jared Cabot